Bone Tumors — MCQs

A 6-year-old boy presents with right hip pain. Physical examination reveals a large mass near the iliac crest. Plain X-ray films show a large lytic lesion of the ilium. MRI studies indicate the tumor originates in the bone and extends into adjacent soft tissues. An incisional biopsy reveals a tumor composed of sheets of small, round, blue cells. What is the most likely diagnosis?

Q28Medium

Which one of the following benign tumors can metastasize to the lung?

Q29Medium

A 10-year-old child presented with a swelling and mild pain around the knee joint along with muscle wasting. X-ray revealed a lesion arising from the epiphysis. Biopsy of the lesion was performed and HPE examination was done. What is the diagnosis?

Q30Easy

What is the largest carpal bone?

Bone Tumors Indian Medical PG Practice Questions and MCQs

Question 21: A middle-aged female presents with a lytic lesion in the lower one-third of the femur. Biopsy showed grooved nuclei and giant cells, with no periosteal reaction. What is the confirmatory investigation for this case?

A. Serum PTH
B. Serum Calcitonin
C. CD1a and Langerin IHC (Correct Answer)
D. MRI

Explanation: ### Explanation The clinical presentation of a lytic lesion in a middle-aged female with specific histopathological findings of **grooved nuclei** (coffee-bean appearance) and **giant cells** is characteristic of **Langerhans Cell Histiocytosis (LCH)**. While LCH is more common in children, it can present in adults, often involving the femur or skull. **1. Why CD1a and Langerin IHC is correct:** LCH is a proliferative disorder of Langerhans cells. On microscopy, these cells show characteristic nuclear grooves. The gold standard for confirmation is **Immunohistochemistry (IHC)**. Langerhans cells are positive for **CD1a, Langerin (CD207), and S-100**. Electron microscopy would show Birbeck granules (tennis-racket shaped), but IHC is the modern confirmatory investigation of choice. **2. Why other options are incorrect:** * **Serum PTH:** Elevated in Brown tumors of Hyperparathyroidism. While Brown tumors are lytic and contain giant cells, they do not feature the characteristic grooved nuclei of LCH. * **Serum Calcitonin:** Used as a marker for Medullary Thyroid Carcinoma; it has no diagnostic value for primary bone tumors. * **MRI:** While excellent for assessing the extent of marrow involvement and soft tissue components, it is not a "confirmatory" investigation as it cannot provide a histopathological or molecular diagnosis. **3. NEET-PG Clinical Pearls:** * **LCH Triad (Hand-Schüller-Christian disease):** Exophthalmos, Diabetes Insipidus, and lytic bone lesions. * **Radiology:** LCH often presents as a "punched-out" lytic lesion without a periosteal reaction. In the spine, it can cause **Vertebra Plana** (Calve’s disease). * **Differential Diagnosis:** Giant Cell Tumor (GCT) also occurs in the distal femur of young adults but is typically **epiphyseal** and lacks grooved nuclei on biopsy.

Question 22: Which of the following statements about fibrous dysplasia is FALSE?

A. It is associated with McCune-Albright syndrome.
B. It is associated with Mazabraud syndrome.
C. It can cause Shepherd's Crook deformity of the femur.
D. Biopsy is contraindicated. (Correct Answer)

Explanation: ### Explanation **Fibrous Dysplasia** is a benign, non-neoplastic condition where normal bone is replaced by fibrous tissue and immature, woven bone. **Why Option D is the Correct (False) Statement:** Biopsy is **not contraindicated** in fibrous dysplasia. While the diagnosis is often made radiologically (showing a characteristic "ground-glass" appearance), a biopsy is frequently performed to confirm the diagnosis or to rule out malignancy (like low-grade osteosarcoma) if the presentation is atypical. Histology classically shows "Chinese letter" patterns of trabeculae without osteoblastic rimming. **Analysis of Other Options:** * **Option A (True):** McCune-Albright syndrome is a triad of polyostotic fibrous dysplasia, café-au-lait spots (Coast of Maine borders), and precocious puberty (hyperendocrinopathy). * **Option B (True):** Mazabraud syndrome is the rare association of fibrous dysplasia (usually polyostotic) with multiple soft tissue myxomas. * **Option C (True):** The "Shepherd's Crook" deformity is a classic complication where the proximal femur undergoes progressive varus deformity due to repeated microfractures in the weakened dysplastic bone. --- ### NEET-PG High-Yield Pearls * **Genetics:** Caused by a somatic mutation in the **GNAS1 gene**. * **Radiology:** Characterized by a **"Ground-glass" appearance** and expansion of the bone with thinning of the cortex. * **Monostotic vs. Polyostotic:** Monostotic (single bone) is the most common form (70-80%). * **Management:** Asymptomatic lesions are observed. Bisphosphonates may help with bone pain. Surgery (curettage and bone grafting) is indicated for impending fractures or significant deformity, though recurrence is common.

Question 23: Which of the following is an epiphyseal origin tumor?

A. Osteoclastoma (Correct Answer)
B. Osteogenic sarcoma
C. Ewing's sarcoma
D. Osteoblastoma

Explanation: **Explanation:** The location of a bone tumor within the long bone (epiphysis, metaphysis, or diaphysis) is a high-yield diagnostic marker in orthopaedics. **1. Why Osteoclastoma is correct:** **Osteoclastoma (Giant Cell Tumor - GCT)** is a classic **epiphyseal** tumor. It typically occurs after the growth plate has closed (ages 20–40). It is characterized by an eccentric location and a "soap-bubble" appearance on X-ray. It originates in the epiphysis but frequently extends into the metaphysis. **2. Why the other options are incorrect:** * **Osteogenic Sarcoma (Osteosarcoma):** This is primarily a **metaphyseal** tumor. It occurs in the most metabolically active growth regions, such as the distal femur or proximal tibia, typically in adolescents. * **Ewing’s Sarcoma:** This is a **diaphyseal** (shaft) tumor. It is a small round blue cell tumor that often presents with an "onion-peel" periosteal reaction. * **Osteoblastoma:** This tumor most commonly involves the **posterior elements of the spine** (lamina and pedicles). When it occurs in long bones, it is usually metaphyseal or diaphyseal, not epiphyseal. **Clinical Pearls for NEET-PG:** * **Epiphyseal Tumors:** Remember the mnemonic **"GEC"** — **G**iant Cell Tumor (Osteoclastoma), **E**nchondroma (in small bones), and **C**hondroblastoma (the only true epiphyseal tumor in children with open physis). * **Metaphyseal Tumors:** Most common site for tumors (Osteosarcoma, Osteochondroma, Simple Bone Cyst). * **Diaphyseal Tumors:** Ewing’s Sarcoma, Adamantinoma, Osteoid Osteoma, and Eosinophilic Granuloma. * **GCT Key Fact:** It is "locally malignant" and the most common site is the **distal femur.**

Question 24: An 8-year-old boy presented with pain in the arm. X-ray demonstrates an expansile lesion in the metaphysis of the upper humerus with breach of the overlying cortex. What is the most likely diagnosis?

A. Aneurysmal bone cyst (Correct Answer)
B. Unicameral bone cyst
C. Chondroblastoma
D. Osteoclastoma

Explanation: ### **Explanation** The correct answer is **Aneurysmal Bone Cyst (ABC)**. **1. Why Aneurysmal Bone Cyst is correct:** ABC is a benign but locally aggressive, blood-filled reactive bone lesion. It typically occurs in the first two decades of life (most common in patients <20 years). Radiologically, it presents as an **eccentric, expansile, "soap-bubble" lesion** in the metaphysis of long bones. A key distinguishing feature of ABC is its ability to **expand and breach/balloon the cortex** (though the periosteum remains intact), often appearing more aggressive than a simple cyst. **2. Why the other options are incorrect:** * **Unicameral Bone Cyst (UBC):** Also known as a Simple Bone Cyst, it is centrally located (not eccentric) and typically does not breach the cortex unless there is a pathological fracture (the "fallen leaf sign"). * **Chondroblastoma:** This is an **epiphyseal** tumor in children. The question specifies a metaphyseal lesion, making this unlikely. * **Osteoclastoma (Giant Cell Tumor):** While it is an expansile, eccentric lesion, it occurs in the **epiphysis** (after growth plate closure) and typically affects the age group of **20–40 years**. It is very rare in an 8-year-old. **3. NEET-PG High-Yield Pearls:** * **Location:** ABC is Metaphyseal; GCT is Epiphyseal; Osteosarcoma/Ewing’s is Diaphyseal/Metaphyseal. * **MRI Finding:** The pathognomonic sign for ABC on MRI is **Fluid-Fluid levels** (representing sedimented red blood cells). * **Genetics:** ABC is associated with the **USP6** gene rearrangement. * **Treatment:** Curettage and bone grafting; however, ABC has a higher recurrence rate compared to UBC.

Question 25: Which of the following tumors typically involves regional lymph nodes?

A. Ewing sarcoma
B. Osteosarcoma
C. Adamantinoma
D. Synovial cell sarcoma (Correct Answer)

Explanation: **Explanation:** In orthopaedic oncology, a fundamental rule is that **most primary bone and soft tissue sarcomas spread via the hematogenous route** (typically to the lungs). Lymphatic spread is rare, occurring in less than 3% of cases. However, certain specific tumors are notorious for involving regional lymph nodes. **1. Why Synovial Cell Sarcoma is Correct:** Synovial cell sarcoma is one of the classic exceptions to the rule of hematogenous spread. Along with Rhabdomyosarcoma, Clear cell sarcoma, Epithelioid sarcoma, and Angiosarcoma, it frequently metastasizes to regional lymph nodes. This makes lymph node assessment crucial in the clinical staging of these patients. **2. Why the Other Options are Incorrect:** * **A. Ewing Sarcoma:** This is a small round blue cell tumor that primarily spreads via the blood to the lungs and other bones. Lymph node involvement is extremely rare. * **B. Osteosarcoma:** The most common primary malignant bone tumor. It characteristically spreads via the bloodstream to the lungs ("skip lesions" are also a feature), but rarely involves the lymphatic system. * **C. Adamantinoma:** A slow-growing, low-grade malignant tumor typically found in the mid-shaft of the tibia. While it can metastasize to the lungs, lymphatic involvement is not a typical feature. **3. NEET-PG High-Yield Pearls:** To remember the tumors that spread to lymph nodes, use the mnemonic **"SCARE"**: * **S:** **S**ynovial Sarcoma * **C:** **C**lear cell sarcoma * **A:** **A**ngiosarcoma * **R:** **R**habdomyosarcoma * **E:** **E**pithelioid sarcoma **Clinical Note:** Synovial sarcoma is most commonly found near joints (though it rarely arises *from* the synovium itself) and often shows a characteristic **biphasic pattern** on histology and a **t(X;18)** translocation.

Question 26: A 22-year-old male presents with a bony mass in the metaphyseal region of the right knee with a typical sun ray appearance. A CT scan of the chest reveals osteoblastic metastases. What is the most probable diagnosis?

A. Osteosarcoma (Correct Answer)
B. Chondrosarcoma
C. Ewing's sarcoma
D. Osteochondroma

Explanation: ### Explanation **Correct Answer: A. Osteosarcoma** The clinical presentation is classic for **Osteosarcoma**, the most common primary malignant bone tumor in young adults. * **Age & Location:** It typically occurs in the second decade of life (10–25 years) and favors the **metaphysis** of long bones, particularly around the knee (distal femur or proximal tibia). * **Radiological Hallmark:** The **"Sunray appearance"** (or sunburst) is caused by a rapid periosteal reaction where the tumor bone forms perpendicular to the cortex. * **Metastasis:** Osteosarcoma is highly hematogenous. The **lungs** are the most common site of metastasis, and the presence of **osteoblastic (bone-forming) nodules** in the chest CT is pathognomonic for metastatic osteosarcoma. --- ### Why Other Options are Incorrect: * **B. Chondrosarcoma:** Usually occurs in an older age group (40–60 years). Radiologically, it shows "popcorn calcification" rather than a sunray appearance. * **C. Ewing's Sarcoma:** Typically affects the **diaphysis** (shaft) of long bones. The characteristic periosteal reaction is **"onion-peeling"** (lamellated), and it is a small round blue cell tumor, not bone-forming. * **D. Osteochondroma:** A benign bone tumor (exostosis). It presents as a pedunculated or sessile growth away from the joint, with a characteristic cartilage cap and continuity with the marrow cavity. --- ### NEET-PG High-Yield Pearls: * **Codman’s Triangle:** Another periosteal reaction seen in Osteosarcoma (elevation of periosteum). * **Serum Marker:** Elevated **Alkaline Phosphatase (ALP)** and LDH levels correlate with tumor burden and prognosis. * **Gold Standard Investigation:** MRI for local staging; Biopsy for definitive diagnosis. * **Treatment:** Neoadjuvant chemotherapy → Limb salvage surgery → Adjuvant chemotherapy.

Question 27: A 6-year-old boy presents with right hip pain. Physical examination reveals a large mass near the iliac crest. Plain X-ray films show a large lytic lesion of the ilium. MRI studies indicate the tumor originates in the bone and extends into adjacent soft tissues. An incisional biopsy reveals a tumor composed of sheets of small, round, blue cells. What is the most likely diagnosis?

A. Chondrosarcoma
B. Ewing sarcoma (Correct Answer)
C. Giant cell tumor of bone
D. Malignant fibrous histiocytoma

Explanation: ### Explanation **Correct Answer: B. Ewing sarcoma** **Why it is correct:** Ewing sarcoma is the second most common primary malignant bone tumor in children and adolescents (typically aged 5–15 years). The clinical presentation of a young child with a large, lytic lesion in a flat bone (like the ilium) or the diaphysis of long bones is classic. The hallmark histopathological finding is **sheets of small, round, blue cells** (primitive neuroectodermal cells) which often contain glycogen (PAS positive). The MRI finding of a large soft tissue component ("extra-osseous extension") is highly characteristic of Ewing sarcoma. **Why the other options are incorrect:** * **A. Chondrosarcoma:** Typically occurs in older adults (40–60 years). Radiologically, it shows "popcorn" calcification or endosteal scalloping, not a purely lytic lesion in a 6-year-old. * **C. Giant cell tumor (GCT):** Usually occurs in young adults (20–40 years) after epiphyseal closure. It is located at the **epiphysis** and shows a "soap-bubble" appearance on X-ray. Histology shows multinucleated giant cells, not small round blue cells. * **D. Malignant fibrous histiocytoma (MFH):** Now often classified as pleomorphic undifferentiated sarcoma, it typically affects older adults and presents with a storiform (wheel-spoke) histological pattern rather than small round cells. **High-Yield Clinical Pearls for NEET-PG:** * **Genetics:** Associated with **t(11;22)** translocation involving the *EWS-FLI1* gene. * **Radiology:** Classic "onion-skin" periosteal reaction (though lytic destruction is also common). * **Markers:** CD99 (MIC2) positive. * **Differential for Small Round Blue Cell Tumors:** Ewing sarcoma, Lymphoma, Rhabdomyosarcoma, and Neuroblastoma. * **Site:** Most common site in the long bones is the **diaphysis**; most common flat bone is the **pelvis**.

Question 28: Which one of the following benign tumors can metastasize to the lung?

A. Osteoid osteoma
B. Non-ossifying fibroma
C. Hemangioma
D. Chondroblastoma (Correct Answer)

Explanation: **Explanation:** **Chondroblastoma** is a rare, benign cartilaginous tumor typically occurring in the **epiphysis** of long bones in young adults (skeletally immature). While histologically benign, it is well-known for its "locally aggressive" behavior. The correct answer is Chondroblastoma because it is one of the few benign bone tumors capable of producing **benign pulmonary implants (metastases)**. These lung lesions are histologically identical to the primary tumor and often grow very slowly or remain indolent, but they represent a classic exception to the rule that benign tumors do not metastasize. **Analysis of Incorrect Options:** * **A. Osteoid Osteoma:** A small, benign osteoblastic lesion characterized by a radiolucent nidus and nocturnal pain relieved by aspirin. It has no metastatic potential. * **B. Non-ossifying Fibroma (NOF):** A common, asymptomatic fibrous cortical defect usually found in children. Most undergo spontaneous regression and never metastasize. * **C. Hemangioma:** A benign vascular tumor, most commonly found in the vertebral bodies (showing a "corduroy cloth" or "jail-bar" appearance). It does not spread to distant organs. **High-Yield NEET-PG Pearls:** * **Benign tumors that metastasize to the lung:** The two most common examples are **Chondroblastoma** and **Giant Cell Tumor (GCT)** of the bone. * **Radiological Hallmark:** Chondroblastoma presents as an eccentric, lytic lesion in the epiphysis with a thin sclerotic rim. * **Histology:** Look for "Chicken-wire calcification" (calcification surrounding individual chondroblasts). * **Treatment:** Curettage and bone grafting; however, regular chest X-rays are recommended during follow-up to monitor for pulmonary nodules.

Question 29: A 10-year-old child presented with a swelling and mild pain around the knee joint along with muscle wasting. X-ray revealed a lesion arising from the epiphysis. Biopsy of the lesion was performed and HPE examination was done. What is the diagnosis?

A. Chondrosarcoma
B. Codman's Tumor (Correct Answer)
C. Osteosarcoma
D. Osteoblastoma

Explanation: ### Explanation The correct diagnosis is **Codman’s Tumor**, also known as **Chondroblastoma**. **1. Why Codman’s Tumor is Correct:** The key to solving this case lies in the **age** and the **anatomical location**. Chondroblastoma is a rare, benign bone tumor that characteristically occurs in the **epiphysis** of long bones (most commonly the distal femur or proximal tibia) in children and adolescents (typically 10–20 years old). * **Clinical presentation:** Mild pain, swelling, and muscle wasting (due to disuse) are classic. * **Histopathology (HPE):** Though not detailed in the prompt, the characteristic finding is a "Chicken-wire" pattern of calcification and "Cobblestone" appearance of chondroblasts. **2. Why Other Options are Incorrect:** * **Chondrosarcoma:** Usually occurs in older adults (40–60 years) and typically involves the metaphysis or diaphysis of flat bones or long bones. It is rare in a 10-year-old. * **Osteosarcoma:** While common in this age group and location (around the knee), it primarily arises from the **metaphysis**, not the epiphysis. X-rays would show a Sunburst appearance or Codman’s triangle (periosteal reaction), which is different from Codman’s Tumor. * **Osteoblastoma:** This tumor most commonly involves the **vertebral column** (posterior elements) and typically presents in the metaphysis or diaphysis if found in long bones. **3. NEET-PG High-Yield Pearls:** * **Epiphyseal Tumors Mnemonic:** "Clear Cell Chondroblastoma" (Clear Cell Chondrosarcoma, Chondroblastoma, and Giant Cell Tumor—though GCT occurs after physeal closure). * **Radiology:** Chondroblastoma appears as a well-defined lytic lesion with a thin sclerotic rim in the epiphysis. * **Treatment:** Curettage and bone grafting.

Question 30: What is the largest carpal bone?

A. Scaphoid (Correct Answer)
B. Lunate
C. Hamate
D. Triquetral

Explanation: **Explanation:** The **Scaphoid** is the largest bone in the **proximal row** of the carpus and is generally considered the largest carpal bone by volume and surface area. It plays a pivotal role in wrist stability, acting as a mechanical bridge between the proximal and distal carpal rows. **Analysis of Options:** * **Scaphoid (Correct):** It is the largest bone of the proximal row. Its boat-like shape allows it to articulate with five bones (Radius, Lunate, Trapezium, Trapezoid, and Capitate). Note: Some anatomical texts debate between the Capitate and Scaphoid; however, in standard medical examinations like NEET-PG, the Scaphoid is the established answer for the largest carpal bone. * **Lunate:** A crescent-shaped bone in the proximal row. It is the most commonly dislocated carpal bone but is significantly smaller than the scaphoid. * **Hamate:** A wedge-shaped bone in the distal row characterized by its "hook" (uncus). While substantial, it is smaller than the scaphoid. * **Triquetral:** A pyramid-shaped bone in the proximal row, smaller than the lunate and scaphoid. **High-Yield Clinical Pearls for NEET-PG:** 1. **Most Common Fracture:** The Scaphoid is the most commonly fractured carpal bone (usually due to a fall on an outstretched hand/FOOSH). 2. **Blood Supply:** It has a **retrograde blood supply** (from distal to proximal). Fractures at the waist or proximal pole are at high risk for **Avascular Necrosis (AVN)** and non-union. 3. **Surface Anatomy:** Tenderness in the **Anatomical Snuffbox** is pathognomonic for a scaphoid fracture. 4. **Capitate Fact:** The Capitate is the first carpal bone to begin ossification (at 1–3 months of age).

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Classification of Bone Tumors

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Benign Bone Tumors

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Malignant Primary Bone Tumors

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Metastatic Bone Disease

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Tumor-Like Lesions of Bone

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Soft Tissue Tumors

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Evaluation and Staging of Bone Tumors

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Biopsy Principles

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Limb Salvage Surgery

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Amputation for Bone Tumors

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Adjuvant Therapies

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Surveillance and Follow-up

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Bone Tumors — MCQs

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